3.2.5 Functions for handling rounding modes

The fegetround() and fesetround functions let you get and set the current rounding mode.

Note:

The following functionality
requires a floating-point model that supports exceptions. In ARM® Compiler 6 this is
disabled by default, and can be enabled by the armclang command-line option -ffp-mode=full.

C99 defines these functions as follows:

int fegetround(void);

int fesetround(int round);

The fegetround() function returns the
current rounding mode. The current rounding mode has a value equal
to one of the C99 rounding mode macros or exceptions.

The fesetround() function sets the current
rounding mode to the value provided. fesetround() returns
zero for success, or nonzero if its argument is not a valid rounding
mode.